63 lines
1.7 KiB
Nix
63 lines
1.7 KiB
Nix
# From: https://gist.github.com/manveru/74eb41d850bc146b7e78c4cb059507e2
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# From: https://discourse.nixos.org/t/string-to-base-64/32624/3
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{ lib, ... }:
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{
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toBase64 =
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text:
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let
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inherit (lib)
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sublist
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mod
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stringToCharacters
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concatMapStrings
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;
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inherit (lib.strings) charToInt;
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inherit (builtins)
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substring
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foldl'
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genList
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elemAt
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length
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concatStringsSep
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stringLength
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;
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lookup = stringToCharacters "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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sliceN =
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size: list: n:
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sublist (n * size) size list;
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pows = [
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(64 * 64 * 64)
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(64 * 64)
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64
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1
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];
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intSextets = i: map (j: mod (i / j) 64) pows;
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compose =
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f: g: x:
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f (g x);
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intToChar = elemAt lookup;
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convertTripletInt = sliceInt: concatMapStrings intToChar (intSextets sliceInt);
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sliceToInt = foldl' (acc: val: acc * 256 + val) 0;
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convertTriplet = compose convertTripletInt sliceToInt;
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join = concatStringsSep "";
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convertLastSlice =
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slice:
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let
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len = length slice;
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in
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if len == 1 then
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(substring 0 2 (convertTripletInt ((sliceToInt slice) * 256 * 256))) + "=="
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else if len == 2 then
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(substring 0 3 (convertTripletInt ((sliceToInt slice) * 256))) + "="
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else
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"";
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len = stringLength text;
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nFullSlices = len / 3;
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bytes = map charToInt (stringToCharacters text);
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tripletAt = sliceN 3 bytes;
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head = genList (compose convertTriplet tripletAt) nFullSlices;
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tail = convertLastSlice (tripletAt nFullSlices);
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in
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join (head ++ [ tail ]);
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}
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